Question

Animals get extinct mainly due to
A. Predation
B. Habitat destruction
C. Afforestation
D. Pollution

Answer 1

Extinction means the permanent disappearance of a species or a population from the earth. There are several reasons for the extinction of organisms. Humans are responsible directly or indirectly for the disappearance of many species on the earth. More than 15000 species are facing the threat of extinction all over the world. The loss of biodiversity and the increased rate of extinction are interrelated.

Complete answer:
Evolutionary studies and fossil studies have developed recently. These studies show that a large number of organisms have become extinct from the Earth. The causes of extinction are also under study. The increased rate of species extinction is largely due to human activities nowadays. Among the different reasons, loss of habitat stands the most important cause of driving organisms to extinction.
The natural habitats of organisms, especially the tropical rainforests all over the world are destroyed and the trees are cut down for the cultivation of economically significant crops and are also converted into grasslands for raising cattle. When the area of habitat is lost, the organisms living in that area will face the threat of extinction due to the lack of food resources and shelter. Some species require large territories and have migratory needs which are badly affected by habitat loss and fragmentation.
Predation is the process of killing one organism by the other organism for feeding or preying. Predation is a natural process which is important to maintain the number of species on the Earth and to transfer the energy to higher trophic levels. An uncontrolled level of predation can cause the extinction of the prey species which eventually leads to the extinction of the predator species also especially if that prey species were their specific food. Over predation by humans has killed birds like the dodo, passenger pigeon, etc.
Afforestation of an area refers to the introduction of new seeds and plant saplings to an area that was not a forest. It can be defined as the artificial built up of a forest which does not cause the extinction of species.
Pollution is the undesirable harmful changes that happen in an environment. Substances that cause pollution are called pollutants. The introduction of pollutants usually causes harm to the existing organisms of the environment. Pollution at a high rate can lead to the extinction of species especially the fishes and amphibians by water pollution.

Thus the correct answer is habitat destruction, option (B).

Note: There are four main reasons for biodiversity losses and species extinctions. They are collectively called ‘The Evil Quartet’. They are - habitat loss and fragmentation, over-exploitation, alien species invasions, and co- extinction. Habitat loss is the loss of an organism’s natural inhabiting area due to increased human activities. Overexploitation is the increased and uncontrolled use of natural resources like fossil fuels, timber, etc. Alien species invasions refers to the introduction of a new species into an area which causes the extinction of the indigenous species of that area. Co-extinctions mean the extinction of different organisms that are associated in certain ways. Organisms with obligate associations would become extinct when the associated organism disappears.